Abundance of vegetable products of the coal period, 59 Accumulation of vegetable matter, 117 Actinolite, 15 Action of internal heat, 128 Action of waves, 107 in forming harbors, 108 Advantages of geological changes, 91 Ætna, 26, 73 Agate, 14 Age of rocks, doubtful-- from change of lithological character, 61 from distance, 61 from disturbance, 61 Alternation of coarse and fine material, 115 Aluminium, 12 Amethyst, 14 Amygdaloidal structure, 17 Ancient volcanic rocks, 29 Andes, granite veins in, 25 Angle of inclination, 71 Anoplotherium, 55 Anticlinal axis, 71 Aqueous causes, 103 Aqueo-glacial action, 120 Argillaceous schist, 20, 31 Arrangement of materials in the crust of the earth, 21 Artesian wells, 92 Asbestos, 15 Atmospheric causes, 95 Atolls, 81 Augite, 15 Auvergne, volcanic district of, 28 B. Basalt, 18 Bed of the sea-- sunken areas in the, 142 why elevated, 145 Belemnites, 52 Breccia, 19 Brine springs-- in Silurian rocks, 35 in the carboniferous formation, 43 in the new red sandstone, 47 C.